Explosive screen cleaner



Patented Nov. 14, 1944 6 Claims.

This invention relates to screen cleaners and more particularly toscreen cleaners of the explosive type and particularly adapted to removeclogging material or debris from the openings in a screen in deep wells.

The primary object of the invention is to provide an explosive cleanerthat will open the passages in. a clogged screen while it is in the wellbore.

Another object is to provide a cleaner that will effect the desiredcleaning operation without damage to the screen liner.

A further object is to provide a cleaner which will effectively cleaneither slotted or perforated screens.

Still another object is to-provide an explosive screen cleaner made upof frangible material so that such material is reduced to a form thatwill not hamper the operations of producing the I wells after the screenhas been cleaned.

Still another object is to provide a cleaner which includes means formaintaining the cleaner assembly centrally of the screen to be cleanedat the time of detonation of the explosive carried by the cleaner.

Another object is to provide a novel method of cleaning well screensthrough the use of an explosive which is so positioned as to give rise'to an explosive impact which emanates from a plurality of spacedcenters.

A more specific object is to provide a screen cleaning assembly whichincludes a central tubular member containing an igniting explosive todischarge the main body of explosive which is carried within spacedfrangible cups mounted upon such member.

The foregoing objects are primary objects and will, together withadditional objects, be more fully apparent from the followingdescription taken in connection with the accompanying drawing in which:

Fig. 1 is a sectional view through a well screen and the upper portionof a cleaner assembly embodying the invention;

Fig. 2 is an elongated view showing an-assembly within a screen and alsoillustrating one construction and manner of discharging the explosive.

The well cleaning device as illustrated in the drawing is lowered upon acable I which may be a conductor cable so that electrical means may beutilized to set off the explosive. Such cable may be an ordinary wirecable attached to the lowering head 2 which is provided with a firingpin 3 having a head 4 for engagement by a memher such as a go-devil 5(Fig. 2) which is dropped over the cable I from the mouth of the wellbore after the assembly, hereinafter described, has been lowered to thedesired position within the screen 6. Alternately it is apparent thatthe explosive used with the device may be discharged by means of anordinary time bomb.

In the embodiment as shown, the lowering head is of relatively sturdyconstruction and it is intended that such head may be repeatedly usablewith explosive assemblies such as that hereafter described. Thisconstruction of the lowering head 2 assists in the rapid lowering of theassembly to the desired position within the well.

The lowering head is threaded internally at 'I to receive the upper endof a small tube 8 of frangible material such as a frangible synthetic,

aluminum and the like. A cap member ID such as an ordinary typeofblasting cap containing fulminate of mercury or like material isplaced on the upper end of the tube 3 and is engageable by the firingpin 3 to initiate combustion of an explosive such as the rod or stringof cordite which is a stick of explosive to some extent, similar to afuse H which, together with a plurality of blasting caps l2, fills theinterior of the tube. While an alternate arrangement of the explosivecordite and the blasting caps has been shown these elements are merelyfor the purpose of conducting the fire from charge to charge ofexplosive. The cordite is found to cause detonation of the explosive itsomewhat better under the existing conditions than does the blastingcaps so that a section of cordite is disposedin each charge ofexplosive.

At spaced intervals along the tube 8 are provided a plurality of annularcups l5 of a frangible material such as a frangible synthetic oraluminum. These cups are of materially smaller diameter than the screen6 but are of a size to contain a proper amount of explosive It such asdynamite that the detonation thereof is effective in producingadesirable explosive force to clean openings l'l adjacent thereto. Thecups l5 are so spaced longitudinally of the tube 8 that their combinedeffect is such as to effectually clean all of the openings l1 throughoutthe length of screen within which the assembly is located. The fireinitiated by the firing pin 3 will travel along the cordite and blastingcaps l2 as a fuse to set ofi the cups of explosive IS in sequence.

To facilitate uniformity in results the invention also contemplates theprovision of a plurality of sets of spring fingers 20 which are attachedto the tube 8 by means of collars 2|. It seems apparent that through theuse oftwo or more of these sets of fingers the explosive as sembly ismaintained concentric with the screen 6 and hence the explosive forceproduced thereby acts'uniformly in all directions.

The operation of the device of the invention is believed apparent fromthe foregoing description. By way of summary it may be stated that theassembly including the tube 8, cups I and the fingers 20 are attached tothe lowering head 2 and lowered by means of the cable I to the desiredposition within the screen 6. The desired explosion is. then initiatedas by means of the go-devil 5 engaging the head 4 of the firing pin 3.The resulting explosion of the cordite I l, the blasting caps l2 and theexplosive charges l4 within the cups I5 is substantially instantaneous,

and sets up a high pressure area in the screen adjacent the cleanerassembly which creates a cleaning the length of screen for which theassembly is designed. While the explosive charges have been shown anddescribed as individual spaced charges, a continuous chargeapproximatingthe length of the area to be cleaned may be used.

Attention is directed to the fact that the use of frangible material forthe tube 8 and the cups I5 is instrumental in providing a minimum ofdebris from the-assembly. This debris may, if

' desired, be removed from within the well but it has been found thatsuch debris offers no difficulty if allowed to remain at the lower endof the well bore.

What is claimed is:

1. An explosive screen cleaner assembly comprising a lowering head, atube of frangible material attached to said head, alternate units of anexplosive and blasting caps arranged end ing head to discharge said capsand the explosive in the containers whereby detonations at a pluralityof spaced points are created.v

2. An explosive screen cleaner assembly comprising a tube of frangiblematerial, a plurality of containers of frangible material surroundingsaid tube in spaced relation, an explosive in said tube and saidcontainers, means for igniting the explosive in said tube proximate oneend thereof whereby the detonation travels along the tube and theexplosive in the containers is detonated, and means for guiding saidassembly centrally of the wallsof a surrounding screen to be cleaned bythe gas pressure generated by the series of,

spaced detonations. I

3. The combination of an assembly for positioning in a well boreincluding a loweringline,

an explosive assembly including a firing mechanism attached to saidline, said assembly including a tubular member having ignition means Itherein, a plurality of annular containers atattached to and surroundingsaid member at spaced intervals, and an explosive insaid containers sothat operation of the firing mechanism operates said ignition means todischarge the explosive'whereby an explosive impact emanates from aplurality of spaced centers to set up a high pressure area in the wellwhich extends the length of said assembly.

4. An explosive device for lowering into a screen including an assemblycomprising a lowering line, a lowering head attached thereto, a tubularmember attached to said head and extending downwardly therefrom, spacedcups attached to said member, an explosive in said cups, and meanswithin said member for firing said 'explo'sive whereby an explosiveimpact is imparted to end within said tube, a plurality of frangiblecontainers surrounding said tube and secured thereto in spaced relation,guiding springs ex tending outwardly from said tube to engage surroundig cylindrical walls to guide the assembly centrally of such walls, andmeans for igniting the explosive in the tube proximate the lowerto'thescr'e'en surrounding the assembly.

5. An explosive screen cleaner including an assembly comprising alowering line, a lowering head attached thereto, a tubular member offrangible material attached to said head and extending downwardlytherefrom, spaced cups of frangible material attached to said member,

an explosive in said cups, and means within said member for firing saidexplosive whereby an explosive impact emanating from a plurality ofspaced centers is imparted to the screen surrounding the assembly.

6. An explosive screen cleaner comprising a tubular member," alternatequantities of an explosive and blasting caps filling said member, meansfor igniting the'explosive atone end of the member, a plurality offrangible containers surrounding said member in spaced relation, and anexplosive in said containers whereby an explosive impact emanating froma plurality of spaced points is created upon the operation of saidIgniting means.

. .MYRON M. KINLEY.

